Stabilized non-corrosive pesticidal composition



STABILIZED NON-CORROSIVE PESTICIDAL COMPOSITION Ralph Rodriguez-Torrent,Winter Park, and Robert N: Fitzwater, Orlando, F121,; dedicated to thefree use ot the People in the territory oi the United States No Drawing.Application March 17, 1953., Serial No. 342,999

4 Claims. (Cl. 167-42) (Granted under Title 35, U. 8. Code (1952), sec.266) A non-exclusive, irrevocable, royalty-free license in the inventionherein described, for all governmental purposes, throughout the world,with the power to grant sublicenses for such purposes, is hereby grantedto the Government of the United States of America.

We hereby dedicate the invention herein described to the free use of thePeople in the territory of the United States to take efiect on thegranting of a patent to us.

This invention relates to the improvement in the storage of liquidpesticidal formulations and the inhibiting of the corrosion of metalliccontainers.

An object of this invention is to stabilize emulsifiable concentrates sothat the components of the concentrates do not react with each other andwith the container with a resultant decrease in efiectiveness.

Another object of this invention is to inhibit the corrosion of thecontainer and prevent the deterioration of the emulsifiable concentrateby adding a material that does not interfere with the properemulsification of the concen trate or reduce the efficacy of theemulsion as an insecticide. Another object of this invention is tostabilize pesticidal emulsifiable concentrates and prevent corrosion oftheir containers.

Another object of this invention is to prevent the loss due to thecorrosion of metals in contact with corrosive oils, such as certainsynthetic products, petroleum fractions, coal tar fractions, and otherproducts of similar nature derived from these.

Another object of this invention is to prevent the loss due to corrosionin industrial concens Where corrosive liquids are held in metal pipes,vats, and tanks, and an inhibitor is needed which is sparingly solubleor not soluble in the liquids.

In many commercial plants the corrosion problem when certain corrosiveliquids run through metal pipes or are held in tanks is serious. Anyorganic liquid or mixture which is of an acid nature, or has an aciditydue to hydrogen bonding will tend to corrode metals. The exact mechanismby which oily liquids and organic solvents attack metals is ratherobscure and of a controversial nature. We have found samples ofisophorone with a pH as low as 3.0 and an acidity which cannot beexhausted by violent water washings. Our invention will minimize,retard, and control the ensuing corrosion, and has the added advantagesof being either not soluble or sparingly soluble in the liquids, ofstable nature, unreactive towards the liquids, and easily washed outwith water or eliminated from the liquids.

This invention is based on the surprising discovery that 2,788,307Patented Apr. 9, 1957 the addition of small amounts of certain metallicthio sulfates and polythionates to emulsifiable concentrate formulationsof insecticidal materials will stabilize these concentrates so that thereaction between the components with deterioration and the ensuingcorrosion is greatly retarded. We have found that in certainformulations of insecticidal emulsifiable concentrates the componentswill react with each other even in glass containers.

Sodium thiosulfate has been found to be an inhibitor of thedeterioration of a formulation consisting of lindane20%, isophorone-40%,an alkylated naphthalene mixture, in this case Velsicol AR-6032.5%, andan emulsifier, in this case Triton X1007.5%. This particular formulationis hereinafter referred to as LIVT. Tests have been made at ordinary ornatural temperatures and accelerated or elevated temperatures. Theresults of a series of insecticidal packages in accelerated storage at49 C. are presented in Table 1.

Table 1.-Efiect of various concentrations of inhibitor on the rate ofdecomposition of LIVT formulations stored in difierent types ofcontainers at 49 C.

Container Percent identlfl- Type of can N 21 8 0 Remarks 1 cationElectrolytic tinplate... 0.05 Severe corrosion, blackish, blacksediment.

.- ..do .05 Removed from oven after 104 days.

do .1 Moderate to severe corrosion, black, black sediment.

d do .1 Removed from oven after 124 days.

e ..do .2 Moderate to severe corrosion, black, black sediment.

f do .2 Removed from oven after 128 days.

g do .2 o.

h "do .5 Very slightly darker in color 1.0 Severe corrosion, darker,

sediment.

1. 0 Removed from oven after days.

1. 0 Removed from oven after 107 days.

1.0 Removed from oven after 96 days.

No significant changes.

Slight precipitate on walls.

Removed from even after 28 days.

Removed from oven after 48 days.

Removed from oven after 63 days.

m 1.25-pound tinplate 1. 0 Terneplate 1. 0

lectrolytic tinplate... 0 1.25-pound tinplate 0 Terneplate 0 Check.

1 When a can became severely eorrod ed and leaked, and the formulationbecame black, acid, and contained sediment, it was removed from thetest.All others were observed at the end of 19 weeks.

The LIVT formulation without inhibitor showed 26 C.) with differentquantities of sodium thiosulfate in.

LIVT are shown'in Table 2.

Table 2. -Efi ect of various concentrations of; inhibitor. on thedecomposition of LI VT formulations in difierent types containers after4 months storage at room temperature ELECTROLYTIC TINPLATE Chemicalanalysis Container Percent Internal Crystaldesignation NazSzO; corrosionlization Color Inorganic Percent 01 lindane 1 O. K Nona... 20.5 0.05 O.K

.2.. .0. K .5 O'.K. 0' SexteroL... Heavy. DaIk.1'ed-.. 5.0 1 4.

1.25-POUND TINPLATEv 1 None e .i 1 do None 20.2 0 Severe dq. Darkernn do18.9

TERNEPLATE a 1 None -No11e o.K'. Ghee- O Slight do 0. Ken.

STANDARD O c... s.

1 Milligrams of inorganic chloride per 0.34 2-gram sample. I u 1Accelerated storage.

At the end of 4 months in normal storage there were no significantdifference in the samples in various containers with different amountsof inhibitor, but as in the accelerated storage test, all of those withthe inhibitor were superior to the check samples. The check samples inall types of containers showed from slight to severe corrosion of thecans, and the chemical analysis and" biological tests on the formulationcorroborated this visual estimation of decomposition. The formulationswith inhibitor in electrolytic tinplate in normal and in 1.25-pounddipped tinplate in accelerated storage were equal to a freshly preparedstandard in both the analytical and toxicity tests against mosquitolarvae and flies.

In Table 3 are shown the results of 7 months con tinuous storage at roomtemperature.

Table 3.--Ejfect of various concentrations of inhibitor on thedecomposition of LIVT formulations in different types of containersafter 7 months storage at room temperature V V ELECTROLYTIC TINPLATEInternal COITOSIOH Container Percent Crystal- Color designation NElnSzOa lization 1 Slightly darker;

I2 01 K5 6O 5 None O. K. 0 Severe-derailed Reddlsh-black.

1.25-POUND TINPLATE I .65 t 1.0 None None". O.K.' Check .0 Severe .-doDarker.

'T'E'RN'EPLA'TE 1.0 None. None... 0. K. 70 Check .0 Slight general.--do. O. K.

1 Eliminated from the test at 5 months. he m am l t er-. 99 h? i WW1?!Storage showed only slight or no corrosion of containers no 7 visiblesediment, and a normal color. The check samples in the three types ofcontainers showed for the terneplate slight general corrosion, for the1.25-pon'nd dipped tinplate severe corrosion, and for the (LS-poundelectrolytic tinplate elimination'because of leaking at the end of 4months of normal storage. From the experimental evidence in the checksamples it is evident that the inhibitor is offering satisfactoryprotection under normal temperature conditions.

Anhydrous sodium thiosulfate has shown slightly better value as aninhibtor at ordinary temperatures while sodium thiosulfate pentahydratehas given better protection at elevated temperatures.

In carrying into practice this invention the finely divided thiosulfatesalt is added freely or in' a porous retainer in the calculate quantityto the emulsifiable concentrate immediately after it has been placed inthe container in which it is to be stored. The container is closedtightly and the contents mixed well by shaking.

A DDT formulation composed of DDT25%, 'alkylated naphthalene-%, and anemulsifier is also protected against deterioration in storage by theaddition of sodium thiosulfate.

Although the examples given herein have contained sodium thiosulfates asthe inhibitor, other water soluble thiosulfates and polythionates, suchas ammonium and potassium may be used. The sodium, potassium, andammonium salts or inorganic polysulfur acids of varying oxygencontent,'such as thiosulfates and polythionates, possess no toxicity inthemselvespand do not interfere with the proper emulsifi c ation of theconcentrate in the quantities used. They are water soluble and will notclog the spray nozzle when used in the spray.

It has. been observed that the addition of Water soluble thiosulfates,viz., sodium thiosulfate, inhibit the decomposition and corrosion of thecontainer in the case of formulations containing other chlorinatedhydrocarbon pesticides. a

Thelthiosulfate salts protect the stability of the pesticidalformulationin glass and metal containers. These thio sulfate salts also inhibit thecorrosion of metallic containers, thus insuring a decrease in loss ofthe contents through leakage.

The thiosulfate salts may also be used to inhibit corrosion inindustrial installations of pipes and tanks, Where normally corrosionwill occur. The optimum amount of the inhibitor to add depends on thespecific conditions under which it is used, such as flow rate throughpipes, size of vats or tanks, and time the liquids are going to be keptin the vats or tanks. In tin-coated containers We have been able to stopcorrosion by acid organic solvents for 3 to 5 months when the inhibitorsodium thiosulfate was used in concentrations of 1% to 0.1% underaccelerated storage temperature of 120 F. Under normal room temperatureconditions corrosion has been stopped for 9 months at least. Theresearch does indicate that for shorter periods of time of storage orcontact between corrosive liquids and metal, concentrations of 0.01% to0.001% or lower may sufiice. The inhibitor may be added freely or inporous bags and any part remaining in the liquid, if necessary, may beeliminated by scrubbing with water and a phase separation.

It is to be understood that the above examples used in describing theuse of these stabilizers and inhibitors are given only as examples andthat this invention is not to be restricted by such use.

We claim:

1. A pesticide comprising lindane2030%, isophorone-40%, alkylatednapthalenes30-3S%, emulsifier-3-l0%, and sodium thiosulfate-0.1-2.0%.

2. A pesticide comprising 20% of lindane, of isophorone, 32% ofalkylated naphthalene, 7.5% of emulsifier, and 0.5% of sodiumthiosulfate pentahydrate.

3. An emulsifiable pesticidal concentrate comprising lindane, alkylatednaphthalenes, isophorone, an emulsifier and an amount of sodiumthiosulfate suflicient to prevent the interaction of the components ofthe concentrate and to prevent corrosion of metallic containers holdingthe same.

4. An emulsifiable pesticidal concentrate comprising lindane, alkylatednaphthalenes, isophorone, an emulsifier, and an amount sufficient toprevent interaction of the components of the concentrate and to preventcorrosion of metallic containers holding the same of a water-solubleinorganic salt selected from the group consisting of the thiosulfatesand polythionates of a member selected from the group consisting ofsodium, potassium, and ammomum.

References Cited in the file of this patent FOREIGN PATENTS 35,060France June 18, 1929 (Addition to Patent 649,934) 844,003 Germany July14, 1952

4. AN EMULSIFIABLE PESTICIDAL CONCENTRATE COMPRISING LINDANE, ALKYLATEDNAPHTHALENES, ISOPHORONE, AN EMULSIFIER, AND AN AMOUNT SUFFICIENT TOPREVENT INTERACTION OF THE COMPONENTS OF THE CONCENTRATE AND TO PREVENTCORROSION OF METALLIC CONTAINERS HOLDING THE SAME OF A WATER-SOLUBLEINORGANIC SALT SELECTED FROM THE GROU CONSISTING OF THE THIOSULFATES ADPOLYTHIONATES OF A MEMBER SELECTED FROM THE GROUP CONSISTING OF SODIUM,POTASSIUM, AND AMMONIUM.